Android中使用Handler（消息机制）造成内存泄露的分析和解决

问题描述：

解决方案：

1、onDestory时清除消息

mHandler.removeCallbacksAndMessages(null); // 参数为null时会清除所有消息。

2、盛行Handler为static并持有Activity的弱引用

public class MainActivity extends Activity {
private static final String tag = "MainActivity";
private TextView mTvShow;
private MyHandler mHandler;

private static final int DELAY_TIME = 10000; // set to 5s and 10s to check result.

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

mHandler = new MyHandler(MainActivity.this);

Log.e(tag, "onCreate");

mTvShow = (TextView) findViewById(R.id.tv_show);

new Thread() {
@Override
public void run() {

mHandler.sendEmptyMessageDelayed(1, DELAY_TIME);
Log.e(tag, "msg send");
}
}.start();

}

@Override
protected void onDestroy() {
Log.e(tag, "onDestroy");
super.onDestroy();
}

static class MyHandler extends Handler {

WeakReference<MainActivity> mWeakActivity;
//强调弱引用
public MyHandler(MainActivity activity) {
mWeakActivity = new WeakReference<>(activity);
}

@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);

MainActivity activity = mWeakActivity.get();

Log.e(tag, "handleMessage," + msg.what);
// 5s为空，10s为空-通知Activity被回收
if (null == activity) {
Log.e(tag, "null");
} else {
Log.e(tag, "not null");
activity.mTvShow.setText("delay show");
}
}
}
}